Radio transmission system



Feb 26 'l J. BETHE'NOD RADIO TRANSMISSION sYsTzl Filed Aug. 2. 1921 n by:

noantoz JOSEPH BETHENOD "115 abt @EL l MW.

Patented Feb. Z6, i924.

mani i JOSEPH BETHENOD, 0F PARIS, E'RAhl'Clily Ennio TRANSMISSION SYSTEM.

Application led August 2, i921. VSerial No. 489,306.

To all whom 'it may concern:

Be it known that I, JOSEPH Bn'rnnnon, a citizen of the Republic ot France, and a resident of Paris, France, have invented certain new and useful Improvements in Radio Transmission Systems, of which the following is a speciiication, accompanied by drawings.

The object of the present invention is to make improvements in radiotelegraphic stations comprising a plurality of high requency generators. The purpose of the invention is to effect by very simple operations and at the will of the oprator, either the simultaneous operation of these generators at the same frequency so as to apply to the antenna the total power of the generating station, or independently to operate these generators at diiierent frequencies so as to obtain a so-called multiplex transmission.

My invention is illustrated in the single ligure of the accompanying drawing.

The principle of the invention consists in the division of the usually net shaped antenna A, extended in one direction, into several sections A1, A2, An, each of which is supplied with current by a high frequency generator G1, G2, Gn, and to provide a device for limiting the currents caused by the electromagnetic or electrostatic induction between any two sections.

In this manner, fn, independent stations will be provided enabling multiplex transmission to the n degree, each station having a wave length slightly diiierent from that of the others. By means of switching means comprising antenna switches S2, Sn, and alternator paralleling switches Sp, Sp, S", the operator mayV at will inter-connect all or a part of the stations, whereby if w23, triplex, or duplex (one transmission having double the power of the other), or simplex transmission is practicable with the total power of the station.

The limiting of the induced currents is preferably .accomplished by means of an arrangement comprising a self-inductance such as I1, I I2, I2, In, In and a capacity C1, CQ, C2, CZ, C, Cn (connected in parallel) which are included in each of the circuits formed by an antenna section, the generator being connected to ground. If the sending is Aof the n, degree, each circuit (1t-1) must be protected by the arrangement (all connected in series). Each or these arrangements or trap circuits should be tuned to one of the frequencies corre@ sponding to one of the n-l other transmissions, so as to provide an almost infinite impedance to said frequencies.

Obviously, the arrangements (trap circuits) o one and the same section may be combined witheach other for reducing Vthe total number of the constitutingfelements.

One of the characteristics of the invention resides in the k,division into a sections of the antenna, in combination with the use ofthe inlinite impedance or so-called frequency traps.

The use of such traps with an undivided antenna would not furnish a practical S0- lution of the problem of multiplex transmission because,inV order ecaciously to protect each generator against the currents generated by the others, very expensive selfinductances and capacities must be provided to avoid serious losses, i. e. a reduction of the output. v This is proved by theory and practicen It may be easily proved that, in case of multiplex operation, the partial use of the antenna has no disadvantage for a given power for each generator.

Having described my invention what I claim is: Y

1. In a Y radio transmission system, an aerial divided into two separate sections adapted to radiate diiierent wave lengths,

generators therefor, and a connection of sub-` stantially infinite impedance in each of said sections to the wave length of the other section for limiting induction eiiects therebetween.

2. In a radio transmission system, an aerial divided into twoV separate sections adapted .to radiate different wavelengths,

generators therefor, a connection of substantially infinite impedance, in each of said sections to the wave length of the other section for limiting induction effects therebetween, and means for connecting both of said generators to the same section.

'3. In. a radio transmission system, an aerial divided into n separate sections adapted to radiate dierent wave lengths, n separate generators, and connections in each of said sections, having infinite impedance to frequencies corresponding to the wave lengths radiated by the other sections.

4. In a radio transmission system, an aerial divided into a plurality of separate sections, a plurality of generators, means for connecting some of said generators toY erate the same frequencies, and. circuits of infinite impedance in each of the radiating sections for limiting self induction from theV other sections.

5, Inj a radio transmission system, an aerial dividedA into n separate sections, n separate generators each of dierent Wave length, connected tosaid sections, and n-l infinite impedance circuits in each section for limiting self induction from the n-l other sections of different Wave length.

6. In a radio transmission system, an aerial divided into two separate sections adapted to radiate different Wave lengths, a pair of generators therefor, and a trap circuit in each section comprising inductanoe and capacity connected in parallel and tuned to the frequency of the other section.

7. In a radio transmission system, an

Vantenna divided into a plurality of sections,

a plurality of generators and means Whereby any desired number of said generators may be utilized to feed any section of said antenna.

8. In a radio transmission system, an antenna divided into a plurality of sections, a plurality of generators and switching means for connecting any desired number of said generators in parallel to any antenna section.

JOSEPH BETHENUD.' 1

aro 

